The pace of growth in the services sector eased for the second month in a row in September, according to the latest NCB Purchasing Managers Index.
The September index showed that growth in the sector remained strong, however, with survey respondents reporting buoyant economic conditions.
One-third of participating firms said their businesses had performed better in September than in August.
The index produced a reading of 57.3 last month, down from 58.1 in August. A reading above 50 indicates expansion.
NCB senior economist Mr Eunan King said activity was continuing to hold up well in the services sector.
The results show that September was the sixteenth consecutive month of growth for services companies.
"The outlook remains optimistic and employment continues to grow," Mr King said.
Business confidence and employment were the strongest components of the index in September.
The confidence reading rose from 73.6 to 75.8 over the month. Firms said growth in new business was fuelling positive expectations for the year ahead as well as driving expansion plans.
Services staff numbers climbed for the thirteenth month in a row as businesses dealt with an upswing in new orders.
Respondent firms pointed to higher levels of new business from both domestic and international firms. Some admitted, however, that they had offered price incentives to their clients to help secure new contracts.